Lithium Complex Oxide for Lithium Secondary Battery Positive Active Material and Method of Preparing the Same

ABSTRACT

Disclosed is a lithium complex oxide and method of manufacturing the same, more particularly, a lithium complex oxide effective in improving the characteristics of capacity, resistance, and lifetime with reduced residual lithium and with different interplanar distances of crystalline structure between a primary particle locating in a internal part of secondary particle and a primary particle locating on the surface part of the secondary particle, and a method of preparing the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

A claim for priority under 35 U.S.C. §119 is made to Korean PatentApplication No. 10-2016-0098648 filed Aug. 2, 2016, Korean PatentApplication No. 10-2016-0130566 filed Oct. 10, 2016, in the KoreanIntellectual Property Office, the entire contents of which are herebyincorporated by reference.

BACKGROUND

Embodiments of the inventive concept described herein relate to alithium complex oxide for a secondary battery and a method of preparingthe same, and more particularly, relate to a lithium complex oxide for asecondary battery, and a method of preparing the same, improving thecharacteristics of capacity, resistance, and battery lifetime withdifferent interplanar distances of crystalline structure between aprimary particle locating on the surface of a secondary particle and aprimary particle locating in the secondary particle by coating differentelements on the surface, in consideration of inclination to functionaldegradation but reduction of residual lithium after a washing forremoving the residual lithium in a preparation process, for a positiveactive material where lithium ion pathways in a-axis and c-axis of acrystalline structure.

With an increase of technology and demand for mobile devices, secondarybatteries as energy sources are increasing in demand. Among secondarybatteries, lithium (Li) secondary batteries are being now commercializedand widely used on the merits of high energy density and operatingpotential, long cycle lifetime, and low discharge rate.

A positive active material for a lithium secondary battery usuallyemploys a lithium-contained cobalt oxide (LiCoO₂). It is also consideredtherefor even to use a lithium-contained manganese oxide such as layeredcrystalline structure of LiMnO₂ or spinel crystalline structure ofLiMn₂O₄, or a lithium-contained nickel oxide such as LiNiO₂.

Among those positive active materials, LiCoO₂ is most frequently usedbecause of good characteristics of battery lifetime and charge/dischargeefficiency, but there is a limit to competitiveness of cost in mass useas power sources for middle/large-scale batteries of electric vehiclesbecause cobalt (Co) is rare and expensive as a resource, and small incapacity. Although the lithium manganese oxide such as LiMnO₂ orLiMn₂O₄, as the positive active material, is low in price, eco-friendly,and highly stable in heat, it is deteriorative in high temperature andcycle characteristics.

A method of preparing a lithium complex oxide generally includes thesteps of manufacturing transition metal precursors, mixing a lithiumcompound and the transition metal precursors, and then baking themixture. During this, LiOH and/or Li₂CO₃ are/is used for the lithiumcompound. It is generally preferred to use Li₂CO₃ in the case that Nicontent of the positive active material is equal to or lower than 65%and preferred to use LiOH in the case that Ni content of the positiveactive material is equal to or higher than 65%.

However, a nickel (Ni) rich system containing nickel equal to or higherthan 65%, reactive at a low temperature, has a problem of having muchresidual lithium which remains in a form of LiOH and Li₂CO₃ on thesurface of a positive active material. The residual lithium, that is,unreacted LiOH and Li₂CO₃ generate gas and a swelling effect by reactingwith an electrolyte in the battery, and then cause high temperaturestability to be seriously worse. Additionally, the unreacted LiOH alsocauses gelation because its viscosity is high when mixing slurry beforemanufacturing electrode plates.

To remove such unreacted Li, a washing process is executed generallyafter preparing a positive active material, thereby much reducingresidual lithium. However, during the washing process, the surface ofthe positive active material was damaged and degraded in characteristicsof capacity and efficiency. Additionally, there was another problem toincrease resistance in high temperature storage. Therefore, it isnecessary to improve the characteristics of capacity, efficiency, andbattery lifetime as well as to reduce residual lithium.

SUMMARY

Embodiments of the inventive concept provide a lithium complex oxide ofa new structure improving the characteristics of capacity, resistance,and battery lifetime as well as reducing residual lithium.

According to an aspect of the inventive concept, a lithium complex oxidesecondary particle formed by coagulation of a plurality of primaryparticles, wherein Co concentration at a boundary of the primaryparticle is higher than Co concentration in the primary particle, thatis in the internal part of the primary particle.

In the lithium complex oxide secondary particle according to theinventive concept, Co concentration of a primary particle at a partwhich is in contact with the surface of the secondary particle is higherthan at a part that is in noncontact with the surface of the secondaryparticle, in the primary particle is locating on a surface part of thesecondary particle.

In the lithium complex oxide secondary particle according to theinventive concept, Co ion concentration is graded, in a primary particlelocating on a surface of the secondary particle, toward a center of theparticle from the surface of the particle. That is, Co ion concentrationmay be higher on the surface than at the center in a primary particlelocating on a surface part of the secondary particle.

In the lithium complex oxide secondary particle according to theinventive concept, a primary particle locating on a surface part of thesecondary particle may have a grade of Co concentration that is reducedin 0.05 to 0.07 mol % per one nm toward a center of the particle.

In the lithium complex oxide secondary particle according to theinventive concept, a primary particle locating on the surface part ofthe secondary particle may be configured to satisfy that dc/dh is 2 to10, where the dc is a length toward a center and the dh is a lengthvertical to the center. That is, primary particles forming the surfaceof secondary particle according to the inventive concept may be shapedin an oval or stick that has an aspect ratio of 2 to 10.

In the lithium complex oxide secondary particle according to theinventive concept, the secondary particle may have at least one peak atpositions (104), (110), (113), (101), (102), and (003) during XRDanalysis. The peaks may be specific peaks generated from LiCoO₂,appearing by a coating with the different metals after a washingprocess.

In the lithium complex oxide secondary particle according to theinventive concept, the secondary particle may have a bound energy (P1)of spin-orbit-spit 2p3/2 peak and a bound energy (P2) of 2p1/2 peak in aCo 2p core-level spectrometry obtained through XPS measurement, whereinthe P1 and the P2 may be ranged respectively in 779 eV≦P1≦780 eV and 794eV≦P2≦795 eV.

In the lithium complex oxide secondary particle according to theinventive concept, the secondary particle may have a ratio of peakintensity (I₅₃₁) around 531 eV and peak intensity (I₅₂₈) around 528.5 eVduring an O 1s core-level spectrometry that is obtained through XPSmeasurement, wherein the ratio may be I531/I528≦2.

In the lithium complex oxide secondary particle according to theinventive concept, the secondary particle has a ratio between peakintensity (I₂₈₉) around 289 eV and peak intensity (I₂₈₄) around 284.5 eVduring a C 1s core-level spectrometry that is obtained through XPSmeasurement, wherein the ratio is I₂₈₉/I₂₈₄≦0.9.

In the lithium complex oxide secondary particle according to theinventive concept, the secondary particle may be given by the followingFormula 1, [Formula1]Li_(x)Ni_(1-(a1+b1+c1))Co_(a1)M1_(b1)M2_(c1)M3_(d)O_(y), wherein, inthe Formula 1, M1 may be Mn or Al, and M2 and M3 are metals selectedfrom a group of Al, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, andZr, and wherein 0.95≦x≦1.05, 1.50≦y≦2.1, 0.02≦a1≦0.25, 0.01≦b1≦0.20,0≦c1≦0.20, and 0≦d≦0.20.

According to another aspect of the inventive concept, a method ofpreparing a lithium complex oxide secondary particle may includemanufacturing precursors of lithium secondary battery positive activematerials given by the following Formula 2, [Formula2]Ni_(1-(x2+y2+z2))Co_(x2)M1_(y2)M2_(z2)(OH)₂, wherein, in Formula 2, M1is Mn or Al, and M2 is a metal selected from a group of Al, Ba, B, Co,Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, and Zr, and wherein 0≦x2≦0.25,0≦y2≦0.20, and 0≦z2≦0.20, reacting precursors of lithium secondarybattery positive active materials with a lithium compound andmanufacturing a positive active material by first thermal treating thereactant, washing the positive active material with distilled water oran alkaline solution, reactively coating the washed positive activematerial with a solution containing M2 that is a metal selected from thegroup of Al, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, and Zr,drying particles of the positive active material, and mixing the driedpositive active material with M3 that is a metal selected from the groupof Al, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, and Zr anddoping the metal M3 into the particles by second thermal treating themixture.

In the method of preparing a lithium complex oxide secondary particleaccording to the inventive concept, the reactively coating may includereactively coating the washed positive active material with the solutioncontaining Co ion.

In the method of preparing a lithium complex oxide secondary particleaccording to the inventive concept, in the reactively coating, athickness of a graded Co concentration part formed on a surface of thesecondary particle may vary according to the solution containing Co.

In the method of preparing a lithium complex oxide secondary particleaccording to the inventive concept, in the reactively coating, thesolution containing Co has concentration of 1 to 10 mol %.

According to still another aspect of the inventive concept, a lithiumsecondary battery includes a lithium complex oxide secondary particleprepared according to embodiments of the inventive concept.

The lithium secondary battery according to the inventive concept may beconfigured to have residual lithium equal to or smaller than 6,000 ppm.

BRIEF DESCRIPTION OF THE FIGURES

The above and other objects and features will become apparent from thefollowing description with reference to the following figures, whereinlike reference numerals refer to like parts throughout the variousfigures unless otherwise specified, and wherein:

FIG. 1 shows a result of measuring diffraction patterns and interplanardistances of an LiCoO₂ positive active material of Comparison 1according to the inventive concept;

FIG. 2 shows a result of measuring TEM and EDX photographs of a positiveactive material prepared according to an embodiment of the inventiveconcept;

FIG. 3 shows a result of measuring diffraction patterns and interplanardistances of a positive active material prepared according to anembodiment of the inventive concept;

FIG. 4 shows a result of measuring TEM and EDX photographs of a positiveactive material prepared according to an embodiment of the inventiveconcept;

FIG. 5 shows a result of measuring diffraction patterns and interplanardistances of a positive active material prepared according to anembodiment of the inventive concept;

FIG. 6 shows a result of measuring respective variations ofconcentration for Ni, Co, and Al toward the center from the surface of apositive active material prepared according to an embodiment of theinventive concept;

FIG. 7 shows a result of measuring an EDX photograph of a positiveactive material prepared according to an embodiment of the inventiveconcept;

FIG. 8 shows a result of measuring diffraction patterns and interplanardistances of a positive active material prepared according to anembodiment of the inventive concept;

FIG. 9 shows a result of measuring TEM and EDX photographs of a positiveactive material prepared according to an embodiment of the inventiveconcept;

FIG. 10 shows a result of measuring respective variations ofconcentration for Ni, Co, and Al toward the center from the surface of apositive active material prepared according to an embodiment of theinventive concept;

FIG. 11 shows a result of measuring respective variations ofconcentration for Ni, Co, and Al toward the center from a third spot ofa positive active material prepared according to an embodiment of theinventive concept;

FIGS. 12 to 14 show results of measuring diffraction patterns andinterplanar distances of positive active materials manufactured bycomparison examples and embodiments of the inventive concept;

FIGS. 15 and 16 show results of measuring EDX photographs of positiveactive materials manufactured by comparison examples of the inventiveconcept;

FIGS. 17 to 19 show results of measuring diffraction patterns andinterplanar distances of positive active materials manufactured bycomparison examples and embodiments of the inventive concept;

FIGS. 20 and 21 show results of measuring respective variations ofconcentration for Ni, Co, and Al toward the center from the surface of apositive active material prepared according to an embodiment of theinventive concept;

FIGS. 22 to 25 show results of measuring XRD of positive activematerials manufactured by comparison examples and embodiments of theinventive concept;

FIG. 26 shows a result of measuring XPS of positive active materialsmanufactured by a comparison example and an embodiment of the inventiveconcept; and

FIGS. 27A to 31E show results of measuring the characteristics ofbatteries including positive active materials manufactured by comparisonexamples and embodiments of the inventive concept.

DETAILED DESCRIPTION

Hereafter, embodiments of the inventive concept will be described indetail with reference to the accompanying figures. The inventive conceptmay not be however restrictive to the embodiments proposed below.

<Comparison 1>

A LiCoO₂ positive active material, which is commercially sold, was usedfor Comparison 1.

<Experimental Example> Measuring Distance Between Crystalline Structures

FIG. 1 shows respective diffraction patterns and interplanar distancesfor a primary particle, which locates in a secondary particle, and aprimary particle locating on the surface part of the secondary particleof the LiCoO₂ positive active material of Comparison 1.

After mounting the LiCoO₂ positive active material on a carbon grid,coating the LiCoO₂ positive active material with carbon and PT, and thenmagnifying the coated LiCoO₂ positive active material in 20 million or25 million times through a TEM pre-treatment that slices the coatedLiCoO₂ positive active material, ten interplanar distances were measuredleft and light around an interplanar distance to be known.

As shown in FIG. 1, diffraction patterns of the primary particleslocating in the internal part of the secondary particle of the LiCoO₂positive active material and locating on the surface part of thesecondary particle were all in hexagonal structure, and interplanardistances of the primary particles locating in the secondary particleand locating on the surface part of the secondary particle were allmeasured as 4.70 nm.

<Embodiment 1> Manufacturing Positive Active Material

First, NiCo(OH)₂ precursors were manufactured through aco-precipitation. Then, a lithium secondary battery positive activematerial was manufactured by adding Li₂CO₃ and LiOH as lithium compoundsto the manufactured precursors, adding Al and Mg as M1 thereto, andprocessing the mixture in first thermal treatment.

After preparing distilled water, the manufactured lithium secondarybattery positive active material was washed by injecting the distilledwater in uniform temperature.

Afterward, the surface of the positive active material was washed andcoated with Co as M2 by agitating the positive active material whileinjecting a cobalt sulfate solution of 0.03 mol into the positive activematerial washing liquid for one hour in a specific ratio, and then driedat 120° C. under a vacuum.

Then, the lithium secondary battery positive active material wasmanufactured by adding Ti as M3 to the coated positive active materialand processing the Ti-added positive active material in second thermaltreatment at 450° C.

<Experimental Example> Measuring TEM and EDX

TEM and EDX photographs were taken from the positive active materialmanufactured through Embodiment 1 and shown in FIG. 2.

As shown in FIG. 2, the positive active material manufactured throughEmbodiment 1 of the inventive concept has Co concentration that ishigher on the surface of the secondary particle and lower toward theinside from the surface of the secondary particle. Co concentration isununiform in the secondary particle with a grade.

<Experimental Example> Measuring Interplanar Distances BetweenCrystalline Structures

FIG. 3 shows respective diffraction patterns and interplanar distancesfor primary particles locating in the internal part of the secondaryparticle manufactured through Embodiment 1 and locating on the surfacepart on which Co and Ti are coated.

As shown in FIG. 3, the thickness of a Co-coated layer is about 80 nm,and the diffraction pattern of the primary particle locating in theinternal part of the secondary particle is in hexagonal structure. Forthe primary particle locating in the secondary particle, 10 adjacentinterplanar distances were measured as 4.88 nm on average in a TEMphotograph. Comparatively, the primary particle locating on the surfacepart having the Co-coated layer was measured as exhibiting a diffractionpattern of hexagonal structure with an interplanar distance of 4.73 nm.

From this result, it can be seen that the interplanar distance of theprimary particle locating on the surface part was relatively reduced incomparison with the primary particle locating in the internal part ofthe secondary particle which was not coated with cobalt, and theinterplanar distance of the primary particle locating on the surfacepart was changed similar to an interplanar distance of LiCoO₂ of acomparison example.

<Embodiment 2> Manufacturing Positive Active Material

A positive active material of Embodiment 2 was manufactured in the sameas Embodiment 1, except that concentration of a cobalt solution added tothe positive active material washing liquid is 4 mol %.

<Experimental Example> Measuring TEM and EDX

FIG. 4 shows a result of measuring TEM and EDX photographs of thepositive active material manufactures through Embodiment 2.

As shown in FIG. 4, it can be seen that the positive active materialmanufactured through Embodiment 2 of the inventive concept has Coconcentration that is higher on the surface of the secondary particleand lower toward the inside of the secondary particle. That is, Coconcentration of the positive active material is ununiform anddistributed in a grade.

<Experimental Example> Measuring Distances Between CrystallineStructures

FIG. 5 shows a result of measuring respective diffraction patterns andinterplanar distances of primary particles locating in the internal partof the positive active material manufactured through Embodiment 1 andlocating on the surface where Co and Ti are coated.

As shown in FIG. 5, it was measured that a thickness of the Co-coatedlayer was about 90 nm, a diffraction pattern of the primary particlelocating in the internal part of the secondary particle was in ahexagonal structure, and an average of 10 adjacent interplanar distancesof the primary particle locating in the internal part of the secondaryparticle was measured as 4.85 nm in a TEM photograph, while the primaryparticle locating on the surface part of the Co-coated layer had adiffraction pattern of hexagonal structure but an interplanar distancethereof was measured as 4.73 nm.

It can be seen that, comparative to the primary particle locating in theCo-uncoated secondary particle, the interplanar distance of the primaryparticle locating on the surface part was reduced and changed similar tothe interplanar distance of LiCoO₂ of a comparison example.

<Embodiment 3> Manufacturing NCM-Based Positive Active Material

In the same manner with Embodiment 1, a positive active material ofEmbodiment 3 was manufactured by executing a coating process with 5 mol% concentration of a cobalt solution added to the positive activematerial washing liquid.

<Experimental Example> Concentration Scanning

FIG. 6 shows a result of measuring respective concentration variationsof No, Co, and Al from the surface of the secondary particle of thepositive active material, which is manufactured through Embodiment 3,toward the center of the particle.

From FIG. 6, it can be seen that the positive active materialmanufactured through Embodiment 3 of the inventive concept has Coconcentration that becomes higher toward the center from the surface inthe Co-coated layer where Co is coated, but after the Co-coated layer,the Co concentration turns to be reduced as close as the center and athickness of the Co-coated layer is 0.1 μm.

<Experimental Example> TEM and EDX

FIG. 7 shows a result of measuring respective EDX photographs for Ni,Co, and Al from the surface of the secondary particle of the positiveactive material, which is manufactured through Embodiment 3, toward thecenter of the particle.

From FIG. 7, it can be seen that the positive active materialmanufactured through Embodiment 3 of the inventive concept has Coconcentration that becomes higher toward the center from the surface inthe Co-coated layer where Co is coated, but after the Co-coated layer,the Co concentration turns to be reduced as close as the center andconcentration of the Co-coated layer is higher along the boundaries ofthe primary particles.

<Experimental Example> Measuring Distances Between CrystallineStructures

FIG. 8 shows a result of measuring respective diffraction patterns andinterplanar distances of primary particles locating in the internal partof the positive active material manufactured through Embodiment 3 andlocating on the surface on which Co and Ti are coated.

As shown in FIG. 8, it was measured that a thickness of the Co-coatedlayer was about 100 nm, a diffraction pattern of the primary particlelocating in the internal part of the secondary particle was in ahexagonal structure, and an average of 10 adjacent interplanar distancesof the primary particle locating in the internal part of the secondaryparticle was measured as 4.84 nm in a TEM photograph, while the primaryparticle locating on the Co-coated layer had a diffraction pattern ofhexagonal structure but an interplanar distance thereof was measured as4.67 nm.

It can be seen that, comparative to the primary particle locating in theCo-uncoated secondary particle, the interplanar distance of the primaryparticle locating on the Co-coated surface was reduced and changedsimilar to interplanar distances of LiCoO₂ of a comparison example.

<Embodiment 4> Manufacturing NCM-Based Positive Active Material

In the same manner with Embodiment 1, a positive active material ofEmbodiment 4 was manufactured by executing a washing and coating processwith 10 mol % concentration of a cobalt solution added to the positiveactive material washing liquid.

<Experimental Example> Measuring TEM and EDX

FIG. 9 shows a result of measuring TEM and EDX photographs on thesurface of the secondary particle of the positive active materialmanufactured through Embodiment 4.

As shown in FIG. 9, it can be seen that the positive active materialmanufactured through Embodiment 4 of the inventive concept has Coconcentration that becomes higher on the surface of the secondaryparticle but turns to be lower as close as the center of the secondaryparticle. Thus, the Co concentration is ununiform in a grade.

Additionally, the EDX measurement shows a Co distribution of bar-shapedprimary particle, from which it can be seen that Co concentration ismeasured as being higher at the periphery of the bar-shaped primaryparticle.

<Experimental Example> Concentration Scanning

FIG. 10 shows a result of measuring respective concentration variationsof No, Co, and Al from the surface of a secondary particle of thepositive active material, which is manufactured through Embodiment 4,toward the center of the particle.

From FIG. 10, it can be seen that the positive active materialmanufactured through Embodiment 4 of the inventive concept has Coconcentration that becomes higher toward the center from the surface inthe Co-coated layer where Co is coated, but after the Co-coated layer,the Co concentration turns to be reduced as close as the center and athickness of the Co-coated layer is 0.14 μm.

<Experimental Example> Concentration Scanning

FIG. 11 shows a result of measuring respective concentration variationsof No, Co, and Al from three spots on the surface of a secondaryparticle of the positive active material, which is manufactured throughEmbodiment 4, toward the center of the secondary particle.

From FIG. 11, it can be seen that three independent spots on the surfaceof the secondary particle of the positive active material manufacturedthrough Embodiment 4 have thicknesses of 0.14 μm that forms a uniformgrade therein.

<Experimental Example> Measuring Distances Between CrystallineStructures

FIG. 12 shows a result of measuring respective diffraction patterns andinterplanar distances of primary particle locating in a secondaryparticle of the positive active material manufactured through Embodiment4 and locating on the surface where Co and Ti are coated.

As shown in FIG. 12, it was measured that a thickness of the Co-coatedlayer was about 140 nm, a diffraction pattern of the primary particlelocating in the internal part of the secondary particle was in ahexagonal structure, and interplanar distance of the primary particlelocating in the internal part of the secondary particle was measured as4.85 nm, while the primary particle locating on the surface, which wascoated with Co and Ti, had a diffraction pattern of hexagonal structurebut its interplanar distance thereof was measured as 4.69 nm.

It can be seen that, comparative to the primary particle locating in theCo-uncoated secondary particle, the interplanar distance of the primaryparticle locating on the Co-coated surface was reduced and changedsimilar to the interplanar distance of LiCoO₂ of a comparison example.

<Experimental Example> Measuring Interplanar Distances BetweenCrystalline Structures at Coated Layer Boundary

FIG. 13 shows a result of measuring a diffraction pattern andinterplanar distances from a boundary between the inside of a primaryparticle, which locates on the surface of a secondary particle of thepositive active material manufactured through Embodiment 4, and a coatedlayer in the primary particle locating on the surface part of thesecondary particle.

As shown in FIG. 13, from the boundary between the inside of the primaryparticle, which locates on the surface of the secondary particle of thepositive active material manufactured through Embodiment 4, and thecoated layer, which is coated with Co and Ti, in the primary particlelocating on the surface part of the secondary particle, the diffractionpattern was in a hexagonal structure and the interplanar distances weremeasured as 4.71 nm on average.

It can be seen that, comparative to the primary particle locating in theinternal part of the secondary particle has an interplanar distance of4.85 nm and the primary particle locating on the surface part of thesecondary particle, which is coated with Co and Ti, has an interplanardistance of 4.69 nm, the interplanar distance of the coated layerboundary in the primary particle locating on the surface part of thesecondary particle coated with Co and Ti, that is, 4.71 nm, was measuredas an intermediate value between the interplanar distance of the primaryparticle locating in the internal part of the secondary particle and theinterplanar distance of the primary particle locating on the surfacepart of the secondary particle which is coated with Co and Ti.

Additionally, it can be seen that the interplanar distance of theprimary particle at the coated layer boundary was changed similar to theinterplanar distance of LiCoO₂ of a comparison example.

<Experimental Example> Measuring Interplanar Distances BetweenCrystalline Structures at Boundary of Primary Particle

FIG. 14 shows diffraction patterns and interplanar distances atboundaries of a primary particle locating on the surface of a secondaryparticle, which is coated with Co and Ti, of the positive activematerial manufactured through Embodiment 4.

As shown in FIG. 14, from the boundaries of the primary particlelocating on the surface part of the secondary particle of the positiveactive material, the diffraction patterns are in a hexagonal structureand the interplanar distances are measured as 4.69 nm and 4.71 nm as anintermediate value of interplanar distances between a core part and acoated layer part.

Additionally, it can be seen that the interplanar distance of theprimary particle at the coated layer boundary was changed similar to theinterplanar distance of LiCoO₂ of a comparison example.

<Embodiment 5> Manufacturing Positive Active Material

In the same manner with Embodiment 1, a positive active material ofEmbodiment 5 was manufactured by manufacturing a lithium secondarybattery positive active material, which had been processed through thefirst thermal treatment, in the composition ofLi_(1.02)Ni_(0.816)Co_(0.15)Al_(0.034)O₂ without addition of Ti.

<Embodiment 6> Manufacturing Positive Active Material

In the same manner with Embodiment 1, a positive active material ofEmbodiment 6 was manufactured by manufacturing a lithium secondarybattery positive active material, which had been processed through thefirst thermal treatment, in the composition ofLi_(1.02)Ni_(0.903)Co_(0.08)Al_(0.014)Mg_(0.003) O₂.

<Embodiment 7> Manufacturing Positive Active Material

In the same manner with Embodiment 1, a positive active material ofEmbodiment 7 was manufactured by manufacturing a lithium secondarybattery positive active material, which had been processed through thefirst thermal treatment, in the composition ofLi_(1.00)Ni_(0.965)Co_(0.02)Al_(0.014)Mg_(0.001) O₂.

<Embodiment 8> Manufacturing Positive Active Material

In the same manner with Embodiment 7, a positive active material ofEmbodiment 8 was manufactured by executing a coating process with 4 mol% concentration of a cobalt solution which was added to the positiveactive material washing liquid.

<Embodiment 9> Manufacturing Positive Active Material

In the same manner with Embodiment 7, a positive active material ofEmbodiment 9 was manufactured by executing a coating process with 5 mol% concentration of a cobalt solution which was added to the positiveactive material washing liquid.

<Embodiment 10> Manufacturing Positive Active Material

In the same manner with Embodiment 7, a positive active material ofEmbodiment 10 was manufactured by manufacturing a lithium secondarybattery positive active material, which had been processed through thefirst thermal treatment, in the composition of Li_(1.00)Ni_(0.985)Al_(0.014)Mg_(0.001)O₂.

The final formulas of compositions used in Embodiments 1 to 10 aresummarized in Table 1 as follows.

TABLE 1 Final Composition FormulaLi_(X1)Ni_(1−(x1+y1+z1))Co_(x1)M1_(y1)M2_(z1)M3_(r1)O_(a) Embodiment 1Li_(1.01)Ni_(0.903)Co_(0.08)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂ Embodiment2 Li_(1.01)Ni_(0.893)Co_(0.09)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂Embodiment 3Li_(1.02)Ni_(0.883)Co_(0.10)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂ Embodiment4 Li_(1.02)Ni_(0.833)Co_(0.10)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂Embodiment 5 Li_(1.02)Ni_(0.786)Co_(0.18)Al_(0.034)O₂ Embodiment 6Li_(1.02)Ni_(0.873)Co_(0.11)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂ Embodiment7 Li_(1.00)Ni_(0.933)Co_(0.05)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂Embodiment 8Li_(1.00)Ni_(0.923)Co_(0.06)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂ Embodiment9 Li_(1.00)Ni_(0.913)Co_(0.07)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂Embodiment 10Li_(1.00)Ni_(0.953)Co_(0.03)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂

<Comparison 2>

In the same manner with Embodiment 4, a positive active material ofComparison 2 was manufactured by injecting active material particlesinto a 0.1 mol cobalt solution, coating the active material with cobaltwhile agitating the mixture, and drying the coated material.

<Comparison 3>

In the same manner with Embodiment 4, a positive active material ofComparison 3 was manufactured, without including Co during a washingprocess, by excluding a Ti adding process and a second thermaltreatment.

<Experimental Example> Measuring TEM and TDX

FIG. 15 shows a result of measuring TEM and EDX photographs from thesurface of a secondary particle of the positive active materialmanufactured through Comparison 2.

As shown in FIG. 15, it can be seen that the positive active materialresulted in an uneven surface, without being doped into the inside,because there was no subsequent thermal treatment even though the Codistribution was concentrated on the surface due to the agitation withthe active material particles which were injected into the cobaltsolution.

<Comparison 4>

In the same manner with Comparison 3, a positive active material ofComparison 4 was manufactured by adding Ti with concentration of 0.001mol and then executing a second thermal treatment.

<Comparison 5>

In the same manner with Comparison 3, a positive active material ofComparison 5 was prepared, without a washing process, aftermanufacturing a lithium secondary battery positive active material whichhad been processed through a first thermal treatment.

<Comparison 6>

In the same manner with Comparison 3, a positive active material ofComparison 6 was prepared by manufacturing a lithium secondary batterypositive active material, which had been processed through a firstthermal treatment, in the composition ofLi_(1.00)Ni_(0.815)Co_(0.15)Al_(0.014)O₂.

<Comparison 7>

In the same manner with Comparison 4, a positive active material ofComparison 7 was prepared by manufacturing a lithium secondary batterypositive active material, which had been processed through a firstthermal treatment, in the composition ofLi_(1.02)Ni_(0.903)Co_(0.08)Al_(0.014) Mg_(0.003)O₂.

<Comparison 8>

In the same manner with Comparison 4, a positive active material ofComparison 8 was prepared by manufacturing a lithium secondary batterypositive active material, which had been processed through a firstthermal treatment, in the composition ofLi_(1.00)Ni_(0.965)Co_(0.02)Al_(0.014) Mg_(0.001)O₂.

<Comparison 9>

In the same manner with Comparison 4, a positive active material ofComparison 9 was prepared by manufacturing a lithium secondary batterypositive active material, which had been processed through a firstthermal treatment, in the composition of Li_(1.00)Ni_(0.985)Al_(0.014)Mg_(0.001)O₂.

The final formulas of compositions used in Comparisons 1 to 9 aresummarized in Table 2 as follows.

The final formulas of compositions used in the first thermal treatmentsof Comparisons 1 to 9 are summarized in Table 2 as follows.

TABLE 2 Final Composition FormulaLi_(X1)Ni_(1−(x1+y1+z1))Co_(x1)M1_(y1)M2_(z1)M3_(r1)O_(a) Comparison 1LiCoO₂ Comparison 2 Washed and dried product of Embodiment 4 Comparison3 Washed and dried product of Comparison 4 Comparison 4Li_(1.00)Ni_(0.933)Co_(0.05)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂ Comparison5 Li_(1.05)Ni_(0.934)Co_(0.05)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂ (Unwashedproduct) Comparison 6 Li_(1.00)Ni_(0.815)Co_(0.15)Al_(0.035)O₂Comparison 7Li_(1.02)Ni_(0.903)Co_(0.08)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂ Comparison8 Li_(1.00)Ni_(0.963)Co_(0.02)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂Comparison 9Li_(1.00)Ni_(0.983)Co_(0.05)Al_(0.015)Mg_(0.001)Ti_(0.001)O₂

<Experimental Example> Measuring TEM and TDX

FIG. 16 shows a result of measuring TEM and EDX photographs from thesurface of a secondary particle of the positive active materialmanufactured through Comparison 4.

As shown in FIG. 16, it can be seen that the positive active materialmanufactured through Comparison 4 has Co concentration uniformlydistributed in the particle, because a Co coating process is notpreformed after manufacturing an active material, and a Co concentrationgrade toward the inside of the particle is not found on the surface.

<Experimental Example> Measuring Distances Between CrystallineStructures

FIG. 17 shows a result of measuring respective a diffraction pattern andinterplanar distances from the surface of a secondary particle of thepositive active material manufactured through Embodiment 4.

As shown in FIG. 17, a diffraction pattern of the surface was in ahexagonal structure and the interplanar distances were measured as 4.85nm on average.

FIG. 18 shows a result of measuring a diffraction pattern andinterplanar distances of a primary particle locating in a secondaryparticle of the positive active material manufactured through Comparison4.

As shown in FIG. 18, it can be seen that the primary particle locatingin the secondary particle of the positive active material has adiffraction pattern of hexagonal structure and interplanar distances of4.83 nm on average. It can be also seen that, even with a second thermaltreatment in the case without a Co coating process, the interplanardistance of the primary particle locating in the secondary particle ofthe positive active material is almost similar to that of a primaryparticle locating on the surface of the secondary particle.

<Experimental Example> Measuring Interplanar Distances BetweenCrystalline Structures at Primary Particle Boundary

FIG. 19 shows a result of measuring diffraction patterns and interplanardistances from a boundary of a primary particle locating on the surfaceof a secondary particle of the positive active material manufacturedthrough Embodiment 4.

As shown in FIG. 19, the primary particle locating on the surface of thesecondary particle of the positive active material was measured ashaving a diffraction pattern of hexagonal structure and interplanardistances of 4.81 nm on average.

Additionally, it can be seen from FIGS. 18 and 19 that, in the casewithout a Co coating process, diffraction patterns and interplanardistances are similar between the inside and the boundary of the primaryparticle.

<Experimental Example> Concentration Scanning

FIG. 20 shows a result of measuring respective concentration of Ni, Co,and Al toward the core from the surface of a secondary particle of thepositive active material manufactured through Comparison 4.

From FIG. 20, it can be seen that the positive active materialmanufactured through Comparison 4 has uniform concentration of Ni, Co,and Al in the particle.

<Experimental Example> Concentration Scanning

FIG. 21 shows a result of measuring respective concentration of Ni, Co,and Al in a direction horizontal to the surface direction of a primaryparticle locating on the surface of a secondary particle of the positiveactive material manufactured through Comparison 4.

From FIG. 21, it can be seen that the positive active materialmanufactured through Comparison 4 has uniform concentration of Ni, Co,and Al in the particle, without a Co concentration grade due to absenceof a CO coating process, and interplanar distances thereof are alsosimilar between the surface and the inside.

<Experimental Example> Measuring XRD

Results of measuring XRD for LiCoO₂ positive active materials ofEmbodiment 4 and Comparison 1 are shown in FIGS. 22 and 23.

As shown in FIGS. 22 and 23, it can be seen that a Co and Ti coatedpositive active material, which is manufactured through Embodiment 4 ofthe inventive concept, is detected with peaks of (104), (110), (113),(101), (102), and (003) as like the case of LiCoO₂ of Comparison 1.

<Experimental Example> Measuring XRD

A result of measuring XRD for a positive active material of Comparison 2is shown in FIG. 24.

As shown in FIG. 24, it can be seen that the positive active materialmanufactured through Comparison 2 of the inventive concept is detectedonly with a peak by Co(OH)₂ but there are no detection with peaks of(104), (110), (113), (101), (102), and (003).

<Experimental Example> Measuring XRD

FIG. 25 shows a result of measuring XRD for positive active materialsmanufactured through Comparison 4, which does not execute a Co coatingprocess, and through Embodiment 4 executing a thermal treatment after aCo coating process.

As shown in FIG. 25, it can be seen that the positive active materialmanufactured through Comparison 4, which does not execute the Co coatingprocess of the inventive concept, is not detected with peaks of (104),(110), (113), (101), (102), and (003) that are distinctly detected fromLiCoO₂.

<Experimental Example> Measuring XPS

FIG. 26 shows results of measuring XPS for positive active materialsmanufactured through Comparison 4, which does not execute a Co coatingprocess, and through Embodiment 3 executing a coating process with acobalt solution which has concentration of 5 mol %.

As shown in FIG. 26, it can be seen that, in the case of coating cobaltduring a washing process according to the inventive concept, the Co 2ppeak intensity is larger, almost due to Co+3, than that of Comparison 4.Additionally, it can be also seen that the peak intensity by Li₂CO₃ ismore reduced than that of Comparison 4.

<Experimental Example> Measuring Residual Lithium

A result of measuring amounts of residual lithium from composite oxidesmanufactured through Embodiments 1 to 10 and Comparisons 4 to 9 issummarized in Table 3 as follows.

To measure residual lithium, an active material of 1 g was precipitatedin distilled water of 5 g and agitated for 5 minutes. Next, filtrate wastaken after the agitation and titration was executed with HCL of 0.1 M.Then, the residual lithium was analyzed by measuring a volume of the HCLuntil pH of the filtrate reaches 5.

From Table 3, it can be seen that active materials manufactured throughembodiments of the inventive concept have residual lithium which isgreatly reduced relative to the case as like as Comparison 5 that doesnot execute a thermal treatment.

TABLE 3 Residual Lithium (ppm) LiOH Li₂CO₃ Total Comparison 4 1043 17872830 Comparison 5 7516 9733 17249 Comparison 6 2628 987 3615 Comparison7 1017 1686 3396 Comparison 8 1744 1622 3366 Comparison 9 1856 2212 4068Embodiment 1 1506 1996 3502 Embodiment 2 1432 1971 3403 Embodiment 31562 1549 3111 Embodiment 4 2142 2450 4592 Embodiment 5 2556 862 3418Embodiment 6 1730 1830 3560 Embodiment 7 1630 2166 3796 Embodiment 82035 2433 4468 Embodiment 9 1569 2067 3636 Embodiment 10 2519 1881 4400

<Manufacturing Example> Manufacturing Battery

Slurry was manufactured by mixing the positive active materials, whichwere manufactured through Embodiments 1 to 10 and Comparisons 4, and 6to 9, super-P as a conducting agent, and polyvinylidenefluoride (PVdF)as a binding agent in weight ratio of 92:5:3. Then an anode for alithium secondary battery was manufactured by uniformly coating theslurry on an aluminum foil which has a thickness of 15 μm, and then bydrying the slurry-coated aluminum foil at 135° C. under vacuum.

A coin battery was manufactured by using the anode and a lithium foil asthe other electrode, using a porous polyethylene film (Celgard 2300 madeby Celgard LLC; thickness of 25 μm) as a separator, and using a liquidelectrolyte in which LiPF6 with concentration of 1.15 M was dissolved ina solvent in which ethylene carbonate and ethylmethyl carbonate aremixed in a volume ratio of 3:7.

<Experimental Example> Measuring Battery Characteristics—InitialCapacity

Results of measuring initial capacities of batteries manufactured withactive materials manufactured through Embodiments 1 to 10 andComparisons 4, and 6 to 9 are respectively shown in FIG. 27A(Embodiments 1 to 4, Comparison 4), FIG. 27B (Embodiment 5, Comparison6), FIG. 27C (Embodiment 6, Comparison 7), FIG. 27D (Embodiments 7 to 9,Comparison 8), and FIG. 27E (Embodiment 10, Comparison 9).

Referring to FIGS. 27A to 27E, the coating process executed according tothe embodiments of the inventive concept contributed to thecharacteristics of capacity and efficiency that was measured as beingmore improved than that of a comparison examples.

Results of measuring initial capacities of batteries manufactured withactive materials manufactured through Embodiments 1 to 10 andComparisons 4, and 6 to 9 are summarized in Table 4 as follows.

TABLE 4 0.1 C Charge/Discharge Charge (mAh/g) Discharge (mAh/g) 1st Eff.(%) Embodiment 1 242.2 215.9 89.1 Embodiment 2 239.9 214.4 89.4Embodiment 3 239.0 215.0 90.0 Embodiment 4 231.7 215.2 92.9 Embodiment 5213.9 194.1 90.8 Embodiment 6 232.5 213.7 91.9 Embodiment 7 248.9 222.389.3 Embodiment 8 247.2 222.5 90.0 Embodiment 9 245.1 220.9 90.1Embodiment 10 251.8 221.6 88.0 Comparison 4 244.5 209.7 85.8 Comparison6 217.1 190.2 87.6 Comparison 7 239.3 211.3 88.3 Comparison 8 255.1219.0 85.9 Comparison 9 258.2 221.6 85.8

<Experimental Example> Measuring Battery Characteristics—Efficiency

Results of measuring efficiency characteristics of batteriesmanufactured with active materials manufactured through Embodiments 1 to10 and Comparisons 4, and 6 to 9 are respectively shown in FIG. 28A(Embodiments 1 to 4, Comparison 4), FIG. 28B (Embodiment 5, Comparison6), FIG. 28C (Embodiment 6, Comparison 7), FIG. 28D (Embodiments 7 to 9,Comparison 8), and FIG. 28E (Embodiment 10, Comparison 9).

Referring to FIGS. 28A to 28E, the coating process executed by theembodiments of the inventive concept contributed to making thecharacteristics of capacity and efficiency measured as being moreimproved than the comparison examples.

Results of measuring the efficiency characteristics of batteriesmanufactured with active materials manufactured through Embodiments 1 to10 and Comparisons 4, and 6 to 9 are summarized in Table 5 as follows.

TABLE 5 ITEM 0.1 C 0.2 C 0.5 C 1.0 C 1.5 C 2.0 C Embodiment 1 100.0%97.6% 94.2% 91.8% 90.2% 89.2% Embodiment 2 100.0% 97.8% 94.5% 92.3%90.9% 89.8% Embodiment 3 100.0% 97.7% 94.6% 92.3% 90.7% 89.6% Embodiment4 100.0% 97.9% 94.5% 91.9% 90.2% 88.9% Embodiment 5 100.0% 98.9% 95.2%92.2% 90.4% 89.0% Embodiment 6 100.0% 97.2% 93.0% 89.9% 88.4% 87.3%Embodiment 7 100.0% 96.9% 93.1% 90.2% 88.4% 86.8% Embodiment 8 100.0%96.7% 92.5% 89.5% 87.4% 85.6% Embodiment 9 100.0% 97.0% 93.2% 90.5%88.8% 87.4% Embodiment 100.0% 96.5% 92.7% 89.7% 87.1% 84.4% 10Comparison 4 100.0% 97.3% 94.2% 92.0% 90.6% 89.6% Comparison 6 100.0%98.3% 94.1% 91.1% 89.4% 88.2% Comparison 7 100.0% 96.3% 92.6% 89.4%86.1% 82.5% Comparison 8 100.0% 96.3% 92.6% 89.4% 86.1% 82.5% Comparison9 100.0% 96.3% 92.6% 89.3% 85.9% 82.3%

<Experimental Example> Measuring Battery Characteristics—Lifetime

Results of measuring lifetime characteristics of batteries manufacturedwith active materials manufactured through Embodiments 1 to 10 andComparisons 4, and 6 to 9 are respectively shown in FIG. 29A(Embodiments 1 to 4, Comparison 4), FIG. 29C (Embodiment 5, Comparison6), FIG. 29C (Embodiment 6, Comparison 7), FIG. 29D (Embodiments 7 to 9,Comparison 8), and FIG. 29E (Embodiment 10, Comparison 9).

Referring to FIGS. 29A to 29E, the coating process executed according tothe embodiments of the inventive concept contributed to making thecharacteristics of lifetime measured as being more improved than thecomparison examples.

Results of measuring the lifetime characteristics of batteriesmanufactured with active materials manufactured through Embodiments 1 to10 and Comparisons 4, and 6 to 9 are summarized in Table 6 as follows.

TABLE 6 Room Temperature Lifetime 50th/1st (%) Embodiment 1 77.4Embodiment 2 80.4 Embodiment 3 78.9 Embodiment 4 74.9 Embodiment 5 89.5Embodiment 6 55.0 Embodiment 7 54.6 Embodiment 8 61.4 Embodiment 9 63.3Embodiment 10 68.5 Comparison 4 77.5 Comparison 6 88.7 Comparison 7 55.0Comparison 8 53.1 Comparison 9 63.0

<Experimental Example> Measuring Battery Characteristics—HighTemperature Storage

As results of measuring high temperature storage characteristics ofbatteries manufactured with active materials manufactured throughEmbodiments 1 to 3 and 5 to 10, and Comparisons 4 and 6 to 9, theresults before storage are respectively shown in FIG. 30A (Embodiments 1to 3, Comparison 4), FIG. 30B (Embodiment 5, Comparison 6), FIG. 30C(Embodiment 6, Comparison 7), FIG. 30D (Embodiments 7 to 9, Comparison8), and FIG. 30E (Embodiment 10, Comparison 9), and the results afterstorage are respectively shown in FIG. 31A (Embodiments 1 to 3,Comparison 4), FIG. 31B (Embodiment 5, Comparison 6), FIG. 31C(Embodiment 6, Comparison 7), FIG. 31D (Embodiments 7 to 9, Comparison8), and FIG. 31E (Embodiment 10, Comparison 9).

Referring to FIGS. 30A to 30E and 31A to 31E, the coating processexecuted by the embodiments of the inventive concept contributed togreatly improving the high temperature storage characteristics becauseimpedances after high temperature storage increased less than those ofthe comparison examples.

Results of measuring the high temperature storage characteristics ofbatteries manufactured with active materials manufactured throughEmbodiments 1 to 3, and 5 to 10 and Comparisons 4, and 6 to 9 aresummarized in Table 7 as follows.

TABLE 7 High Temperature Storage (Ohm) Before Storage After StorageEmbodiment 1 4.5 16.1 Embodiment 2 4.3 16.6 Embodiment 3 4.3 13.1Embodiment 5 4.4 28.5 Embodiment 6 6.2 6.7 Embodiment 7 5.0 10.0Embodiment 8 4.5 8.6 Embodiment 9 4.5 8.7 Embodiment 10 7.2 28.4Comparison 4 20.8 40.3 Comparison 6 10.0 96.2 Comparison 7 21.9 60.6Comparison 8 348.9 656.0 Comparison 9 434.5 498.0

According to embodiments of the inventive concept, it may be allowableto improve a secondary battery in the characteristics of capacity,resistance, and lifetime with different interplanar distances ofcrystalline structures between a primary particle locating on thesurface part of a secondary particle and a primary particle locating inthe internal part of the secondary particle by coating differentelements and washing in the processes of forming precursors and/or anactive material.

While the inventive concept has been described with reference toexemplary embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the inventive concept. Therefore, it shouldbe understood that the above embodiments are not limiting, butillustrative.

1. A lithium complex oxide secondary particle formed by coagulation of aplurality of primary particles, wherein Co concentration at a boundaryof the primary particle is higher than Co concentration in the primaryparticle.
 2. The lithium complex oxide secondary particle of claim 1,wherein Co concentration of a primary particle at a part which is incontact with the surface of the secondary particle is higher than at apart that is in noncontact with the surface of the secondary particle,in the primary particle is locating on a surface part of the secondaryparticle.
 3. The lithium complex oxide secondary particle of claim 1,wherein Co ion concentration is graded, in a primary particle locatingon a surface of the secondary particle, toward a center of the particlefrom the surface of the particle.
 4. The lithium complex oxide secondaryparticle of claim 1, wherein a primary particle locating on a surfacepart of the secondary particle has a grade of Co concentration that isreduced in 0.05 to 0.07 mol % per one nm toward a center of theparticle.
 5. The lithium complex oxide secondary particle of claim 1,wherein a primary particle locating on a surface part of the secondaryparticle is configured to satisfy that dc/dh is 2 to 10, where the dc isa length toward a center and the dh is a length vertical to the center.6. The lithium complex oxide secondary particle of claim 1, wherein thesecondary particle has at least one peak at positions (104), (110),(113), (101), (102), and (003) during XRD analysis.
 7. The lithiumcomplex oxide secondary particle of claim 1, wherein the secondaryparticle has a bound energy (P1) of spin-orbit-spit 2p3/2 peak and abound energy (P2) of 2p1/2 peak in a Co 2p core-level spectrometryobtained through XPS measurement, and wherein the P1 and the P2 areranged respectively in 779 eV≦P1≦780 eV and 794 eV≦P2≦795 eV.
 8. Thelithium complex oxide secondary particle of claim 1, wherein thesecondary particle has a ratio of peak intensity (I₅₃₁) around 531 eVand peak intensity (I₅₂₈) around 528.5 eV during an O 1s core-levelspectrometry that is obtained through XPS measurement, and wherein theratio is I₅₃₁/I₅₂₈≦2.
 9. The lithium complex oxide secondary particle ofclaim 1, wherein the secondary particle has a ratio between peakintensity (I₂₈₉) around 289 eV and peak intensity (I₂₈₄) around 284.5 eVduring a C 1s core-level spectrometry that is obtained through XPSmeasurement, and wherein the ratio is I₂₈₉/I₂₈₄≦0.9.
 10. The lithiumcomplex oxide secondary particle of claim 1, wherein the secondaryparticle is given by the following Formula 1,Li_(x)Ni_(1-(a1+b1-+c1))Co_(a1)M1_(b1)M2_(c1)M3_(d)O_(y),  [Formula 1]wherein, in the Formula 1, M1 is Mn or Al, and M2 and M3 are metalsselected from a group of Al, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P,Sr, Ti, and Zr, and wherein 0.95≦x≦1.05, 1.50≦y≦2.1, 0.02≦a1≦0.25,0.01≦b1≦0.20, 0≦c1≦0.20, and 0≦d≦0.20.
 11. A method of preparing alithium complex oxide secondary particle by claim 1, the methodcomprising: manufacturing precursors of lithium secondary batterypositive active materials given by the following Formula 2,Ni_(1-(x2+y2+z2))Co_(x2)M1_(y2)M2_(z2)(OH)₂,  [Formula 2] wherein, inFormula 2, M1 is Mn or Al, and M2 is a metal selected from a group ofAl, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, and Zr, and wherein0≦x2≦0.25, 0≦y2≦0.20, and 0≦z2≦0.20; reacting precursors of lithiumsecondary battery positive active materials with a lithium compound andmanufacturing a positive active material by first thermal treating thereactant; washing the positive active material with distilled water oran alkaline solution; reactively coating the washed positive activematerial with a solution containing M2 that is a metal selected from thegroup of Al, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, and Zr;drying particles of the positive active material; and mixing the driedpositive active material with M3 that is a metal selected from the groupof Al, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, and Zr anddoping the metal M3 into the particles by second thermal treating themixture.
 12. The method of claim 11, wherein the reactively coatingcomprises: reactively coating the washed positive active material withthe solution containing Co.
 13. The method of claim 11, wherein, in thereactively coating, the solution containing Co ion has concentration of1 to 10 mol %.
 14. A lithium secondary battery comprising a lithiumcomplex oxide secondary particle of claim
 1. 15. The lithium secondarybattery of claim 14, wherein the lithium secondary battery is configuredto have residual lithium equal to or smaller than 6,000 ppm.